JP3712621B2 - Refractory structure of melting furnace - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a refractory structure of a melting furnace for melting incineration ash such as sewage sludge, municipal waste and industrial waste, and incineration ash discharged from an incinerator such as a commercial thermal power plant.
[0002]
[Prior art]
Conventionally, incineration ash such as sewage sludge, municipal waste, and industrial waste has been melted by an ash melting furnace and taken out as molten slag and molten metal in order to achieve resource recycling, volume reduction, and detoxification. .
That is, in order to melt the incineration ash in the furnace body using such a melting furnace, for example, the incineration ash discharged from the waste incinerator is introduced into the furnace body through various conveying means and supply means. The injected incineration ash is melted with high-temperature plasma. The molten slag and molten metal generated in the melting furnace are discharged from the tap through the tap, led to the slag pit and metal pit via the conveyor, and used for various purposes. .
[0003]
By the way, the inner peripheral wall of the furnace body of the melting furnace has a fireproof structure because it is exposed to high temperature, and a brick refractory is placed at the position of the slag line that is the boundary line between the molten slag and the gas atmosphere. Has been. In addition, a refractory material for a gas phase brick is disposed in the upper part of the brick and in a gas atmosphere.
As such a slag line position brick and a brick located in a gas atmosphere, a material containing a relatively small amount of SiC fired in an oxidizing atmosphere is used. In addition, the outer peripheral part of the furnace main body is covered with a water cooling jacket provided via a stamp and an iron skin, and the outer peripheral part of the furnace main body is cooled by cooling water flowing through the inside of the water cooling jacket.
[0004]
[Problems to be solved by the invention]
However, in the refractory structure of the conventional melting furnace mentioned above, SiO ₂ and a molten slag SiC to SiO ₂ and during firing were present originally in a small refractory of SiC amount at the slag part refractories are generated by oxidation In response, she was eroded. Further, if the amount of SiC in the slag part refractory is small, the thermal conductivity is low and the cooling effect is not sufficient, which promotes erosion.
On the other hand, when using a large amount of SiC as the conventional vapor phase refractory, oxidation by exhaust gas proceeds at a higher speed than erosion of the slag portion refractory, so that the slag portion refractory below is upward and lateral The refractory temperature increased and the erosion was expected to accelerate due to two-sided heating.
[0005]
The present invention has been made in view of such a situation, and an object of the present invention is to improve the thermal conductivity by using a refractory material with a large amount of SiC, to extend the life by increasing the cooling effect, and to provide a furnace for molten slag and the like. An object of the present invention is to provide a refractory structure for a melting furnace capable of improving the corrosion resistance of a main body.
[0006]
[Means for Solving the Problems]
In order to achieve the above-described problems of the prior art, in the present invention, silicon carbide aggregate is formed by mixing metal Si and carbon, and any or all of Si, Al, Fe, and C as antioxidants. hints, calcined in a non-oxidizing atmosphere, place a 90 wt% or more including self-sintering type refractories of the SiC, the inner peripheral wall of the furnace body located near the boundary line between the molten slag and the gas atmosphere, the An oxide-based refractory is disposed on the inner peripheral wall of the furnace body in a gas atmosphere at the top of the refractory, and a joint material of SiC 90 wt% or more is filled between the refractory and the oxide-based refractory. ing.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on illustrated embodiments. Here, FIG. 1 is a schematic sectional view showing a melting furnace to which the fireproof structure according to the embodiment of the present invention is applied. As shown in FIG. 1, the plasma ash melting furnace 1 of the present embodiment has a furnace body 2 having a fireproof structure formed in a bottomed cylindrical shape, and a molten slag 3 is provided on a lower side surface of the furnace body 2. An outlet 6 for discharging the molten metal 4 and the exhaust gas 5 and an outlet 7 having a downward slope are provided. The molten slag 3 is discharged from the furnace body 2 of the melting furnace 1 by an overflow method that overflows through the outlet 6.
In addition, a main electrode 8 and a furnace bottom electrode 9 connected to a DC power supply device (not shown) are disposed at the upper and lower centers of the furnace body 2, and nitrogen gas is sent to the main electrode 8 from a nitrogen gas generator (not shown). It is comprised so that it may be supplied, and when the incinerated ash thrown in is heated with the high temperature plasma 10, it will fuse | melt. For this reason, an ash charging port (not shown) for charging incineration ash such as waste into the furnace body 2 is provided on the upper side surface of the furnace body 2 opposite to the tap hole 6.
[0009]
The inner peripheral wall of the furnace body 2 is installed on the slag brick 12 provided in the vicinity of the height position of the slag line L, which is a boundary line between the molten slag 3 and the gas atmosphere 11, or on the slag brick 12. A large number of refractories such as gas phase bricks 13 are arranged without gaps along the circumferential direction and stacked, and joint material (mortar) 14 is provided between adjacent bricks in the vertical and circumferential directions. Filled. The outer peripheral portion of the furnace main body 2 is covered with a water cooling jacket 16 provided via a filler stamp 15 and an iron skin, and the outer periphery of the furnace main body 2 is cooled by cooling water flowing inside the water cooling jacket 16. The part is cooled.
[0010]
The said slag part brick 12 is provided in the location which contacts the molten slag 3 of high temperature (1400-1600 degreeC). Therefore, as the slag portion brick 12, a self-bonding type (self-bonding) or silicon nitride-bonded refractory containing SiC of 90 wt% or more, preferably SiC of 95 wt% and fired in a non-oxidizing atmosphere is used. . When the SiC amount is 90 wt% or less, the corrosion resistance against the molten slag 3 is not sufficient, and the cooling effect of the furnace body 2 is also insufficient.
[0011]
The silicon nitride bonding type is a method in which silicon carbide aggregate is mixed with metal Si and molded, and heated in a nitrogen atmosphere to form Si ₃ N ₄ to form a bonding material. The self-sintering mold is formed by mixing silicon carbide aggregate with metal Si and carbon, and heating in a non-oxidizing atmosphere (including firing refractories together with carbon breaths) to form SiC. Is the method.
And the joint material 14 between the slag part bricks 12 is formed with the mortar of SiC 90 wt% or more. As the antioxidant, any or all of Si, Al, Fe, and C are included.
[0012]
Further, the gas phase brick 13 is made of an oxide refractory containing chromium or the like at a location in contact with the exhaust gas 5 in the gas atmosphere 11. In the plasma melting furnace 1 of the present embodiment, ash is melted by Joule heat generation of current flowing in the slag, so the slag is not less than 1250 ° C. (about 1400 to 1600 ° C.) which is the melting temperature of the ash, and the refractory surface temperature It was about 1000-1100 degreeC. Further, the inside of the furnace was a reducing atmosphere, and the atmosphere temperature was about 1000 to 1300 ° C., which was lower than the slag temperature. Since the slag is overflowed, the slag may rise and fall by several tens of millimeters depending on the output situation, but the liquid level is basically constant.
[0013]
In the refractory structure of the melting furnace 1 according to the embodiment of the present invention, the refractory constituting the inner peripheral wall of the furnace body 2 includes SiC 90 wt% or more in the vicinity of the slag line L exposed to the high temperature of the molten slag 3, A self-bonding or nitriding bond-type slag brick 12 fired in an oxidizing atmosphere is disposed, and a gas-phase brick 13 of an oxide-based refractory in a gas atmosphere 11 affected by the exhaust gas 5 above the slag brick 12. Therefore, the corrosion resistance against the molten slag 3 and the exhaust gas 5 can be improved.
This result is shown in FIGS. FIG. 2 shows an erosion graph when the SiC content is increased for the slag brick 12, and the SiC content is any when the test temperatures are 1250 ° C., 1300 ° C., 1400 ° C., and 1500 ° C. It turns out that the amount of erosion is reducing that it is 90 wt% or more. Further, FIG. 3 shows erosion data comparing SiC and Cr ₂ O ₃ in the gas phase part, and the erosion amount of the oxide refractory containing chromium is smaller than that of the SiC refractory. It can be seen that it is better to use the latter oxide-based refractory containing chromium or the like as the vapor phase brick 13.
Moreover, in the fireproof structure of the present embodiment, the wettability with respect to the molten slag 3 is deteriorated due to the presence of the slag brick 12, the penetration of the molten slag 3 is suppressed and the hardness is high, and thus the high hardness increases and the slag flow is prevented. Abrasion resistance is high, and durability of the furnace body 2 can be improved.
In addition, since the refractory structure having a large amount of SiC is used in the refractory structure of the present embodiment, the cooling effect can be enhanced along with the improvement of thermal conductivity, and the life of the furnace body 2 can be extended. Moreover, since the joint material 14 of SiC 90 wt% or more is filled between the slag part bricks 12, it prevents the molten slag 3 from entering between these bricks due to the damage of the joint material 14, and the durability of the furnace body 2. Property can be further improved.
[0014]
While the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and changes can be made based on the technical idea of the present invention. For example, in the above-described embodiment, the present invention is applied to the furnace body 2 of the plasma ash melting furnace 1, but the refractory structure of the present invention is applied to a melting furnace such as a resistance melting furnace other than the plasma ash melting furnace or an arc type melting furnace. You may do it.
[0015]
【The invention's effect】
As described above, the refractory structure of the melting furnace according to the present invention is formed by mixing silicon carbide aggregate with metal Si and carbon, and includes any or all of Si, Al, Fe, and C as an antioxidant. It was calcined in a non-oxidizing atmosphere, to place the SiC of 90 wt% or more including self-sintering type refractory material, the inner peripheral wall of the furnace body located near the boundary line between the molten slag and the gas atmosphere, the refractory An oxide refractory is disposed on the inner peripheral wall of the furnace main body in a gas atmosphere, and a joint material of SiC 90 wt% or more is filled between the refractory and the oxide refractory . Therefore, the thermal conductivity is improved, the cooling effect is enhanced, the corrosion resistance and wear resistance against the molten slag are improved, the life of the furnace body can be extended, and damage to the joint material due to the molten slag can be avoided. And the molten slag It is possible to prevent the slag portion from entering between the refractories and further improve the durability of the furnace body. In addition , according to the fireproof structure of the present invention, it is possible to prevent the refractory in the slag portion from being heated from the two upper and lateral surfaces to rise in temperature and eroded at an accelerated rate .
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a melting furnace to which a refractory structure according to an embodiment of the present invention is applied.
FIG. 2 is an erosion graph showing the relationship between the SiC content and the erosion amount of the refractory in the slag part.
FIG. 3 is a diagram showing the amount of erosion when SiC and Cr ₂ O ₃ are compared in the gas phase part.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Plasma ash melting furnace 2 Furnace main body 3 Molten slag 4 Molten metal 11 Gas atmosphere 12 Slag part brick 13 Gas phase part brick 14 Joint material L Slag line

Claims (1)

A mixture of metal Si and carbon and formed into silicon carbide aggregate, and including Si, Al, Fe, either or all of the C as an antioxidant, was fired in a non-oxidizing atmosphere, the SiC least 90 wt% including The self-sintering refractory is disposed on the inner peripheral wall of the furnace body located near the boundary line between the molten slag and the gas atmosphere, and is the upper part of the refractory and the inner peripheral wall of the furnace body in the gas atmosphere. A refractory structure for a melting furnace, characterized in that an oxide-based refractory is disposed on the surface, and a joint material of SiC 90 wt% or more is filled between the refractory and the oxide-based refractory .

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